The attacker was killed by Afghan Forces and an injured U.S. service member is undergoing treatment, the NATO-led Resolute Support mission said.

KABUL — A member of the U.S. armed forces was killed and another was wounded in an apparent insider attack in the Afghan capital Kabul on Saturday, the NATO-led Resolute Support mission said.

“Initial reports indicate the attacker was a member of the Afghan National Defense and Security Forces. Initial reports also indicate the attacker was immediately killed by other Afghan Forces,” the Resolute Support mission said in a statement.

No details have been released about the attacker’s motives or affiliations, and the statement said an investigation is underway.

The wounded service member was evacuated to Bagram Airfield for medical treatment and remains in stable condition, the statement said.

Defense Secretary James Mattis said in September that training and vetting of Afghan forces was being stepped up to minimize insider attacks and some training and advisory operations have been scaled back while security is assessed.

Last month, the NATO commander in Afghanistan, General Scott Miller, escaped unhurt when the bodyguard of a provincial governor opened fire on a group of U.S. and Afghan officials in the southern province of Kandahar.